| Integrated switching power supplies have been widely used in communication systems, computers, and consumer electronics etc. Motivated by portable applications that demand high performance, switching power supplies are developed mainly aiming to high efficiency, high precision and high integration.At first, with overview of the development of modern switching power supply, the target of the controller was presented. Then, based on the design target of chip system, the system architecture of the controller was proposed. The efforts were focused on its efficiency improvement, chip area reduction, system reliability and tradeoff between output voltage ripple and efficiency. In order to decrease the area of the chip, self-lift circuit is introduced, so PMOS power switch which occupy much area can be replaced by NMOS. While, precision of output voltage is also quite important, and switch frequency vary with temperature and input voltage change, so PLL is introduced to achieve this target.After completing the System architecture, some key modules like bandgap reference, error amplifier, PWM comparator, PLL, self-lift circuits, current sensor and some protection circuits were given and simulated in 0.35 um technology.The controller chip system was completed based on the system architecture and circuit modules. Some typical Electrical characteristics were simulated and analyzed. The system simulation results showed that the chip has a high speed of system response, wonderful line regulation and load regulation. The precision of the output is also as high as 99.95%. All specifications of the controller were successfully achieved. |
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